19694665740521 has 2 divisors, whose sum is σ = 19694665740522. Its totient is φ = 19694665740520.

The previous prime is 19694665740461. The next prime is 19694665740527. The reversal of 19694665740521 is 12504756649691.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10529732952025 + 9164932788496 = 3244955^2 + 3027364^2 .

It is an emirp because it is prime and its reverse (12504756649691) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19694665740521 - 2¹⁴ = 19694665724137 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (19694665740527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9847332870260 + 9847332870261.

It is an arithmetic number, because the mean of its divisors is an integer number (9847332870261).

Almost surely, 2^{19694665740521} is an apocalyptic number.

It is an amenable number.

19694665740521 is a deficient number, since it is larger than the sum of its proper divisors (1).

19694665740521 is an equidigital number, since it uses as much as digits as its factorization.

19694665740521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 97977600, while the sum is 65.

The spelling of 19694665740521 in words is "nineteen trillion, six hundred ninety-four billion, six hundred sixty-five million, seven hundred forty thousand, five hundred twenty-one".